STR: 1.) In Nightly, open the following URL in a new tab: https://www-demo2.allizom.org/firefox/reading/start/ 2.) Click the reader icon in the main address bar once the page has loaded, to enter Reader View. Expected results: Reader View should display content from the top half of the page, which is contained in `<header role="content-info">`. It used to display the opening paragraph, and the main heading <img>. I would consider both of these to be pretty relevant to the rest of the article content. Actual results: Only content from the bottom half of the page is displayed in Reader View. Content in the main page <header> is ignored completely. This seems to be a recent regression, as the header was displayed in Reader View fine last week. As a side note: I also now frequently get the error "Failed to load article from page" when toggling Reader View, when applying only very small changes to the markup (for example, wrapping an <h3> and <p> in a plain <div> for layout/styling). This makes it very difficult to create a page for Reader View with any kind of visual design that may require additional markup in places.
A little further investigation shows this seems to be triggered by the `role` attribute on the <header>. I've been testing role="banner" and role="content-info" landmarks, and both seem to cause Reader View to ignore the content. If I remove the landmark role, Reader View seems to display the <header> content as expected. I'm going to remove the landmark role from the page, but will leave this bug open as I'm not sure if this is intended behavior.